Funnel for stretch-spinning cuprammonium staple fiber



y 5, 1964 OSAMU OKAMURA 3,131,429

FUNNEL FOR STRETCH-SPINNING CUPRAMMONIUM STAPLE FIBER Filed Feb. 6 1961INVENTOR. OSA MU OKAMURA United States Patent 3,131,429 FUNNEL FQRSTRETCH-SPINNING CUPRAM- MQNIUM STAELE FIBER Osamu Olramura,Nobeolra-shi, Japan, assignor to Asahi Kasei Kogyo Kabushilri Kaisha,Osaka, Japan, a corporation of Japan Filed Feb. 6, 1961, Ser. No. 87,256Claims priority, application Japan May '24, 1360 1 Claim. (Ci. 188) Thisinvention is concerned with a method for economically manufacturingcuprammonium staple fiber which has excellent strength or both excellentstrength and elongation by the so-called down-flowing stretch spinningmethod, and a spinning funnel employed therefor.

In the previously known down-flowing stretch spinning method employedfor manufacturing cupramrnonium rayon, a spinning solution extrudedthrough a spinneret into the funnel is first stretched by a down-flowingstream of a coagulating liquid and simultaneously coagulated partiallyto form filaments, and secondly is further stretched, being coagulatedmore and more, by tension of winding from outside in addition to thestream, with the result that the filaments have a higher speed than theflowing speed of the coagulating liquid and finally are stretched asmuch as several hundred times in the funnel. The manufacture ofcuprammonium staple fiber is by the same principle, too. However, so faras an apparatus is concerned, it is not the same, because of the factsthat, (1) in the production of staple fiber, it is absolutely necessaryto separate the adjacent fibers from each other so that the staplefibers are not conglutinated to each other; (2) denier of each staplefiber ranges widely from 1 to 3.0 or more up to such as 5.0 and 7.0,while denier of rayon normally is 1.0-1.5; and (3) the total denier ofthe fibers produced from one funnel is requested to be large enough tosuch a degree as desired from economical view point. From the foregoing,it will be seen that long resident period of time in the funnel isrequired for the spinning solution to complete coagulation, that is tosay, total length of the funnel must be long, and diameter of thespinneret should be made larger. In the conventional funnel, diameter ofthe spinneret was more than 8 cm., and whole length of the funnel morethan 100 cm. When cuprammonium staple fiber is produced by the use ofsuch type of spinning funnel, the spinning solution extruded through thespinneret is coagulated slowly in the long funnel and stretched slowlyunder tension according to such proceeding of slow coagulation.

According to the various recent studies on spinning of regeneratedcellulose, however, it has been found that the physical properties ofthe regenerated fiber, such as tenacity and elongation dependconsiderably on how coagulation of filaments is effected at the timewhen they are stretched in the spinning process, and that fiber ofexcellent physical properties are obtained only when filament inadequately coagulated state is stretched. Notwithstanding such studies,cuprammoniurn staple fiber now on sale we not satisfactory in physicalproperties. It shows that the combination of coagulating and stretchingis not successful. Recently, improvements in physical properties of theartificial cellulose fibers are desired, accompanying with appearance ofvarious synthetic fibers. Particularly at present when the blendedspinning of the former and the latter is strongly demanded, increases oftenacity and elongation, as well as breaking energy, and improvement inresin finishing property of the artificial fibers are highly desired.

Various attempts to improve the physical properties are reported. Forexample, there are so-called aftertensioning, i.e., various tensions aregiven to filaments just after leaving the spinning funnel, and a methodwherein rapid stretching of filaments is effected by means of flow of acoagulating liquid while the filaments are not completely coagulated inthe funnel to make them fine and then contacted to the coagulatingliquid for comparatively long period of time. Although the improvementin tenacity could be attained by such ways, reduction of elongation ofthe product filaments cannot be avoided since the tension is given undera severe condition or for comparatively long period of time. Theartificial cellulose fiber having only some strength but poor elongationhas improved crystallization and crystalline rearrangement in thefilament, but lacks elastic portion, with the result that the fiber isbrittle and has small breaking work energy and poor resin finishingproperties.

In the accompanying drawings, FIG. 1 is a vertical section view of anexemplified spinning funnel of the invention and FIG. 2 is a verticalsection view of a spinning funnel employed heretofore. It is an objectof the present invention to provide a method and a funnel formanufacturing cuprammonium staple fiber having high tenacity, elongationand uniform sectional structure.

The present invention will be fully explained hereinunder, comparingwith the conventional method.

In the conventional method, the spinning funnel as et forth in FIG. 2 isemployed for spinning. The transformation process of thread in this casewill be minutely explained in connection with its faults. The spinningsolution extruded through the spinneret into the funnel as mentionedabove is at the first lightly stretched by means of coagulating liquidflowing in the funnel and at the same time, subjected to coagulatingaction by the coagulating liquid to form a partially coagulated state,but the stretching given at this stage is not so high that a higherdegree of micell rearrangement is not formed within the partiallycoagulated filaments. This is the first fault. After this stage, thecoagulation of the filaments is gradually advanced with ammoniadiffusion from the filaments. Breaking of once formed skin structure ofthe filaments cannot be avoided since the strong stretching is continuedeven after passed a point where rapid turbulent diffusion occurs. Thisis the second fault. After all, the product filaments has unevensectional structure, thereby to not provide the filaments with superiorphysical properties.

While, according to the present invention, the method is provided thatthe spinning solution is extruded through spinneret into the funnel toform partially coagulated filaments which are strongly stretched bymeans of a rapid fiow of the coagulating liquid to provide with a higherdegree of micell rearrangement reasonably, and thereafter the filamentsare relaxed by sudden decrease of flow speed of the coagulating liquid,and then they are completely coagulated. By the use of such method, thefilaments become, in the first rapid stretching stage, fine enough thatit needs hardly any further stretching, and in the second stage therelaxation of the tension by sudden decrease of flow speed of thecoagulation liquid causes the micell rearrangement provided in theprevious rapid stretching to be adequately moderated, and thencoagulation is completed to fix the moderated micell rearrangement.Thus, excellent fiber having quite even sectional structure andincreased tenacity as well as elongation is obtained.

Then, the apparatus for carrying out the method of the invention, i.e.spinning funnel, will be fully explained hereinunder.

The present invention is fully described referring to the accompanyingdrawing. In FIG. 1, 6 is spinneret mounting means, 4 is a spinneret, andl is a conical tube located under and distanced from the spinneret 4 toprovide with suficient space to introduce a coagulating liquid. A spinning solution is fed from an upper flowing pipe to means 6 anddischarged through a number of fine holes into the coagulating liquid.The coagulating liquid is fed from the bottom of cylindrical tube '7surrounding conical tube part of the conical tube by the action of thecoagulating liquid since the conical tube is short in its length and issuddenly narrowed. If the coupling of the conical tube with the straightlong tube is not made flat, the spinning 1, and flows into conical tube1 accompanying with the 5 solution extruded through the orifice of theperiphery part spinning solution. The spinning solution and the coaguofthe spinneret runs down and adheres to the lower Wall lating liquid flowdown through the conical tube and pass surface of the conical tube dueto the greater effect of the through a straight long tube 2 of smallerdiameter, wherespeed and the weight thereof than the effect of the flowin the spinning solution is not completely coagulated so of thecoagulating liquid, thereby causing difiiculties in that it is drawn tothe utmost possible extent by torrent 1 the spinning operation. However,if the inside diameter of the coagulating liquid. 3 is a coagulationtube or an d of the lower end of the conical tube is 1.2-2.0 times asexpanded straight tube whose diameter is greater than. that much as theinner diameter d of the straight long tube of the tube 2, and the lowerend of the tube 2 is inserted and the coupling part coupling these tubesis made flat, into the closed upper end of tube 3. The torrent of theadhesion of the spinning solution to the lower wall surface coagulatingliquid in tube 2 enters suddenly the coagulaof the conical tube isprevented and furthermore the flow tion tube 3 so that flowing speed issuddenly and greatly of the coagulating liquid is not disturbed. Theinner direduced. The filaments drawn to the utmost extent are ameter ofthe straight long tube d may be varied dependloosed or relaxed and arecompletely coagulated. ing upon the amount of the coagulating liquid andthe The filaments in tube 3 are taken out by drawing applied spinningspeed, but it is so decided that the flowing speed from the outsidereeling or winding device without being of the coagulating liquid in thetube is 254 2 times of almost subjected to further stretching. thespinning speed. But it should not be less than 1.5 The spinning funnelapparatus for cuprammonium stacm. The length of the straight long tube 2is adequately ple fiber employed heretofore is as shown in FIG. 2. Thevaried depending upon the elongation required for the spinning solutionextruded through the spinneret is subproduct, and it is $5 times of thetotal length of the jected to moderate tension and elongation by thecomparafunnel. The inner diameter d of the tube 3 is so detertively longconical tube and the coagulation tube so that mined that the flowingspeed of the coagulating liquid is the stretching of the filaments undertension proceeds 2 2 times of the spinning speed. But, it should noteven at the lower part of the coagulation tube where the be less than2.0 cm., and the inner diameter d of the cocoagulation is considerablyadvanced. Consequently, the agulation tube should in all cases be largerthan the inside filaments are subjected to unreasonable tension. Thus,diameter d of the straight long tube. The spinning speed use of theconventional apparatus necessarily gives inferior stated herein isdefined by the speed of the filaments at the filaments in tenacity andelongation in comparison with outlet of the coagulation tube 3. thataccording to this invention since adequate crystal- Experimental valuesof some examples of the method lization and micell rearrangement in theinner structure and the spinning funnel apparatus of this invention willof the filaments are not obtained in the case of the conbe set forth,comparing with that of the conventional apventional apparatus. paratus.The spinning solution employed is a cuprarn- In the preferred embodimentof the apparatus, the monium cellulose solution (10% cellulose, 7.3%ammoupper inside diameter d of the conical tube 1 is not more nia, and3.65 copper) produced by the method known than 2 times of the diameterof the spinneret 4 (more than heretofore.

Dimension of the funnel Physical properties of the filaments Method 13L1 DS DE Ws WE (111111.) B; (mm) (mun) L2 (111111.) Den. (g./d.) (per-(g.ld.) (percent) cent) Conventional 125 35 320 1,280 1.5 2.43 14.2 1.6219.0 method 125 35 320 1, 220 2.0 2. 14.1 1.58 19.5 155 35 550 1.930 3.02. 54 15.5 1.72 19.1

1 2 d1 11 l1 11 (111111.) (mm) (mun) (mm) (mm) (mm) Method of the 120 2035 180 800 800 1.5 3.22 121.5 2.20 24.3 prescntin- 120 20 35 180 400 1,000 1.5 3.05 18.0 2.13 21.9 vention (A) 120 20 35 180 800 1,500 2.0 3.0117.0 2.13 20.0 120 25 35 180 800 1,500 2.0 3. 25 15.6 2.15 20.2 Methodeithe i 155 30 800 1, 230 3.0 2. 08 17.3 2.31 21.3 present in- 20 35 180400 1, 000 1.5 3.31 1 1.3 2. 41 13.9 vention (B) 120 20 35 400 1, 9002.0 3.23 14.6 2.03 21.0 30 35 400 400 1,580 3.0 5. 22 15.4 2. 25 18.8

Method A: Increased both tenacity and elongation. Method B: Increasedonly tenacity.

8 cm.), and that the length 1 of the conical tube is within /5 of thetotal length of the funnel, though it may be adequately varied dependingupon denier or the filaments to be spun, total denier (more than 1,000denier) and total length of the funnel (more than 100 cm). The insidediameter d of the lower end of conical tube should be larger than theinner diameter d of the straight long tube 2, Le, 1.2-2.0 times as muchas the d and the coupling part coupling the conical tube with thestraight long tube should be made fiat and horizontal. This is becausethe spinning solution extruded through the spinneret is rapidlycollected in the central What I claim is:

Apparatus for stretch spinning of cuprammonium staple fiber, comprisinga spinneret, a sharply downwardly convergent conical tube having anupper inside diameter a and a lower inside diameter d and a verticaldimension L the ratio of diameters d zd ranging from (1245.5) :(l.86)and L ranging from 18-40, said conical tube further having a flat bottomand being positioned beneath said spinneret, a long straight tubeconnected to said fiat bottom and having an inside diameter ri and acoagulation tube connected to the bottom of said long tube, the insidediameter (i of the lower flat end of the conical tube being greater thanthe inside diameter d of the long tube in a ratio of 1.2-2, and theinside diameter of the coagulation tube being greater than the insidediameter of the long tube.

References Cited in the file of this patent UNITED STATES PATENTS1,590,594 Taylor June 29, 1926 6 Elsaesser Oct. 25, 1927 Hartmann Oct.20, 1931 Knehe July 14, 1942 Aizawa et a1 Aug. 21, 1962 OTHER REFERENCES

